Ladder.



H. S. THOMPSON. LADDER. APPLICATION FILED JAN. 19, 1912.

Patenbed Aug. 27, 1912.

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HEEIRY S. THUMPSON, "In? BEACON, lll'ICliil'tliAN.

LADDER,

osses-is Application filed Jaiiuary 19, 19' 3.

Specification of Letters Patent.

Fateiited Aug; 23?, 191%, Serial $22,105

adapted for use in mines and having various advantages, hereinafter pointed out.

The invention consists in a. ladder having its rungs secured to the side rails by means of bolts, and includes also various details 01 coi'istruction as hereinafter fully pointed out and as illustrated in the accompanying drawings, in which Figure 1 is a detail perspective of the ladder; Fig. 2 is a detail side elevation thereof; Fig. 3 is a detail in perspective of :1

splice bar adapted for use in uniting a plu-v rality of sections oi. the ladder; and Fig. t is a sectional View on the line l- -l of Fig. 1. The side rails or bars 10 and ii of the ladder are of steel, and for some of the pun poses of the invention are channeled in their outer faces, as shown at 12. The rungs 13 are preferably tubular for the purpose of lightness, but in any event are upertured from their ends, and the ends of the bore or the end apertures are threaded, the one with a right hand and the other With a left hand thread. The ends oi the rungs abut against the inner faces of the side rails, and bolts 14, 15, correspondingly threaded, are inserted through suitable apertures in the side rails. The heads of these bolts are preferably square and are adapted to fit within the channel. 12, and the bolts are thereby prevented from being turned in connecting up a rung" the bolts screwed in until their heads are practicttlly in contact with the side bars and are brought into position to enter the channels thereof. The bolts being now held against rotation, a, pipe wrcnchis applied to the rum; and the bolts are thereby drawn up "tightly.

The ladders are provided with as many rungs as may be desirable, and are made of any preferred length. that a, longer ladder is required than the length iil which they are ordinarily made,

il heu it is found two ladders may be united by placing the lower ends oi the side rails of one. againstthe upper ends ot the side oils of the other. The bolts securing one or more 0:" the rungs of each section are removed and splice bars 16 are applied to the outer faces of the side rails. 'ihose arc-spertured to receii'e the bolts, their apertures heiug spaced aptirt the same distance as the apertures in the side rails the ladder sections. The bolts being now inserted, are drawn up in the same manner has been described, thus securely binding the two sections of the ladder together.

llhen the channel form of side rail is used the splice hers made with a, longitudinal rib 17' for entering the channel, and are themselves chamieled in their outer faces, as shown at 118., to engage sud hold the heads of the bolts. Braces may also be secured to the ladder by means of the rung bolts A hortion of a brace bar is shown at it and preferably has the same cross-sectional form as his side rsilsz The bar is apertur to receive one of the rung bolts, and is secured to the ladder by first removing; the bolts from one ot' the riu I thou inserting}, one or". these bolts tl'irough the brace bar and the side rail of the ladder. iyhereugon the rung is tightened up in iruu'iner already dcscril'icd, the head of the bolt securing the brace entering the channel in the outer face thereof. Tie brace bars may, of course, be of any suitable length and may he stra ght or may be bent, as necessary to bring their outer ends into engagement. with the framing; or other structure to which thifil to be secured.

The ladder thus constructed has various advantages, among which are the followiupu-lt is of the knock-Flor n type, that is to say, it may be readily assembled emtaken apart in the position Where it is tended to be used, no blaclrsmithiiig or inochin' 1g being required. The various parts may be made up in quantities and shipped to the user before assembling, and the nu her of "parts necessary to build up it is of. the desired length having been Corr e to the place of use they may be put toget -r by an unskilled laborer lhe rungs being :Clii'ttl in piece by ii'iezrns of-stud bolts, the use of nuts b-e m tions' are entirely covered and protected against i'uoisture, thereby preventing a tendavoided, the threzllied port-1h ency to rust and making it possible to separate the ladder into its elements even after long use, these elements being in no Wise injured. by the operation and being capable of being reassembled for use elsewhere. This is a consideration of importance in the operation of mines, for the reason that heretofore it has been found that when the use of a mine shaft has been discontinued it has not been profitable to attempt to Withdraw the ladders for use in other shafts.

It is of importance that all mining appliances shall be so constructed as to elimi nate the danger of accidents so far as pos sible. The use of round rungs in metal ladders has heretofore been hazardous because of their tendency to turn and permit the foot of the. user to slide off, with great liability that he will fall and be injured. By the use of the right and left screw threads and the employment of bolts which are held against turning, this danger may be entirely eliminated. In assembling the ladder the left hand threaded end of the rung is'placed at the left side, so' that in turning up the rung it is turned outwardly or in the direction it Will tend to turnas the foot of the user is applied to it. The rung being turned up tightly in assembling it cannot, of course, be turned by the foot of the user, but the pressure incident to use will tend to hold it tightly in'place.

In building up a ladder of two or more sections by the use of splice bars of such form that they have an interlocking engagement with the side rails, and by securing these splice bars by means of the rung bolts, the ladder is even stronger at the place where spliced than in other portions, and economy of material is secured. The item of economy is also secured by the use of brace bars, as described, or atleast.

a bar having in itsouter face a recess for receiving the head of the attaching bolt.

I claim as my invention 1. In a ladder, in combination, a pair of channeled side rails having bolt holes, rungs having their ends abutting against the inner faces of the rails and having oppositely threaded apertures in their ends, and bolts securing the rungs to the side rails, the heads of the bolts being polygonal and fitting Within the channels of the rails.

2. In a ladder, in combination, a plurality of ladder sections, each section comprising a pair of channeled side rails, rungs having their ends abutting against the, inner faces of the rails, and bolts securing the rails to the rungs the heads of the bolts being polygonal and fitting Within the channels ot the rails; a d splice bars connecting the side rails of adjacent sections and being cured thereto by means of bolts securi the rungs of each section, each splice b..- having a longitudinal rib for entering the channels of theside rails to which it is applied and having a channel in its outer face for receiving the bolt-head.

3. In a ladder, in combination, a. pair of side rails having bolt holes, rungs having their ends abutting against the inner faces of the rails and having oppositely threaded apertures in their ends, and bolts having polygonal heads for securing the rungs to the side rails, and a brace bar secured to the outer face of one or" the side rails by one of the rung-securing bolts, such brace having a channel in its outer face for receiving the bolt-head.

' HENRY s. THOMPSON.

lVitnesses LOUIS K. GILLSON, E. M. Kna'ronun. 

